Effects of anthraquinone extract from Rheum officinale Bail on the physiological responses and HSP70 gene expression of Megalobrama amblycephala under Aeromonas hydrophila infection.

We evaluated the effect of dietary supplementation with anthraquinone extract (from Rheum officinale Bail) on the resistance to Aeromonas hydrophila infection in Megalobrama amblycephala. The fish were randomly divided into two groups: a control group (fed a standard diet) and a treatment group (standard diet supplemented with 0.1% anthraquinone extract) and fed for 10 weeks. We then challenged the fish with A. hydrophila and recorded mortality and changes in serum cortisol, lysozyme, alkaline phosphatase (ALP), total protein, aspartate aminotransferase (AST), alanine aminotransferase (ALT), and hepatic catalase (CAT), superoxide dismutase (SOD), malondialdehyde (MDA) and the relative expression of heat shock protein 70 (HSP70) mRNA for a period of 5 d. Supplementation with 0.1% anthraquinone extract significantly increased serum lysozyme activity before infection, serum ALP activity at 24 h after infection, serum total protein concentration 12 h after infection, hepatic CAT activity 12 h after infection, hepatic SOD activity before infection, and the relative expression of hepatic HSP70 mRNA both before infection and 6 h after infection. In addition, the supplemented group had decreased levels of serum cortisol 6 h after infection, serum AST and ALT activities 12 h after infection, and hepatic MDA content 12 h after infection. Mortality was significantly lower in the treatment group (86.67%) than the control (100%). Our results suggest that ingestion of a basal diet supplemented with 0.1% anthraquinone extract from R. officinale Bail can enhance resistance against pathogenic infections in M. amblycephala.

Effects of anthraquinone extract from Rheum officinale Bail on the growth performance and physiological responses of Macrobrachium rosenbergii under high temperature stress.

In order to study the effects of anthraquinone extract from Rheum officinale Bail on Macrobrachium rosenbergii under high temperature stress, freshwater prawns were randomly divided into five groups: a control group was fed with basal diet, and four treatment groups fed with basal diet supplemented with 0.05%, 0.1%, 0.2%, and 0.4% anthraquinone extracts for 10 weeks, respectively. Then, freshwater prawns were exposed to high temperature stress at 35 degrees C for 48h. The growth, changes in haemolymph total protein, aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), lysozyme, nitrogen monoxide (NO) and hepatic catalase (CAT), superoxide dismutase (SOD) and malondialdehyde (MDA) were investigated. The results showed that compared the control group, the specific growth rates, feed conversion efficiency, haemolymph ALP and lysozyme activities, total protein contents, hepatic CAT and SOD activities increased while haemolymph AST, ALT and hepatic MDA contents decreased in treatment groups before the stress, but their levels did not correlate with the doses of anthraquinone extracts. The specific growth rate (SGR), feed conversion efficiency and haemolymph lysozyme activity significantly increased but haemolymph AST activity decreased in 0.1% dose group; whereas haemolymph ALP activity and feed conversion efficiency increased but ALT activity and hepatic MDA contents significantly decreased in 0.2% dose group before the stress compared with the control. After high temperature stress, 0.1-0.2% anthraquinone extract also could improve the haemolymph total proteins, lysozyme and ALP activities, hepatic catalase, and superoxide dismutase, and reduce haemolymph ALT and AST activities, hepatic malondialdehyde contents. The cumulative mortality in the control was about 100% at 48h after high temperature stress while the cumulative mortality in the treatment groups supplemented with 0.1-0.2% anthraquinone extract were about 48-65%. The artificial infection with Vibrio anguillarum also showed the cumulative mortality in the control was about 100% while the cumulative mortality in the treatment groups supplemented with 0.1-0.2% anthraquinone extracts were about 57-80%. The present study suggested that ingestion of a basal diet supplemented with 0.1-0.20% anthraquinone extracts could prevent high temperature stress and promote the growth of prawns.